Power tools



Feb. 21, 1956 L. G. PERETTI ETAL 2,735,908

POWER TOOLS Filed Sept. 19, 1952 INVENTOR. Ieonar'd QPer-etti BY Joseph (ZRa/th/ ATTORNEYS.

United States Patent POWER TOOLS Leonard G. Pe'retti, Chicago, and Joseph J. Rath, Shiller Park, Ill.

Application September 19, 1952, Serial No. 310,406

2 Claims. (Cl. 20061.92)

This invention relates to power tools, and more particularly to an improved means for preventing operation of a power tool of the type having a key-operated chuck unless the key is properly stored in the tool.

A main object of the invention is to provide a novel and improved means for preventing the loss of a key of a power tool of the type having a key-operated chuck, as well as preventing the tool from being operated unless the key is properly stored in the tool, the improvement involving relatively simple structure, providing a great improvement in the safety of operating the tool, and preventing loss of the chuck key.

A further object of the invention is to provide an im proved power tool of the type having a key-operated chuck, the improvement involving inexpensive structure, greatly improving the safety of operation of the tool, and providing a convenient and positive means for preventing loss of the chuck key.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure 1 is a side elevational view of a power tool according to the present invention, shown with the chuck key thereof engaged with the chuck of the tool.

Figure 2 is an enlarged fragmentary elevational view of a portion of the handle of the power tool, said portion being partly broken away to reveal the interior details of construction, and showing the manner in which the chuck key is housed in the handle.

Figure 3 is a bottom view of the handle of the tool, showing the aperture provided to receive the chuck key.

Figure 4 is an enlarged cross sectional detail view taken on the line 44 of Figure 2.

Referring to the drawings, 11 designates a power tool having a chuck 12 of the key-operated type, such as, for example a Jacobs type of chuck. The chuck is operated by a key 13 which has a transverse handle bar 14 and a shank 15, said shank being provided with the chuck-engaging bevel gear 16 and with the axial end stud 18. The key is further formed with the diametrically opposed radially extending arms 19, 19 having respective upstanding portions 20, 20.

The handle of the tool is shown at 21 and includes the horizontal partition wall 22 which carries the housing 23 for the main control switch of the tool, said control switch being operated by the trigger member 24 in the conventional manner. The tool is energized by a line cord 25 which is wired in series with the control switch 23, and which is also wired in series with a stationary switch contact 26 and a flexible switch contact 27 insulatingly mounted on the horizontal partition wall 22, as shown in Figure 2. The flexible switch contact 27 is located below the stationary switch contact 26 and normally is out of engagement with the switch contact 26, whereby the energizing circuit of the tool cannot be closed by the main control switch 23.

Integrally formed with the horizontal partition 22 is the depending vertical cylindrical socket 28 having threaded into its top end the plug 29, said plug being located below the intermediate portion of the flexible switch contact 27. Extending slidably through the center of the plug 29 is the plunger rod 30 through the bottom end of which extends the transverse pin 31. The transverse pin 31 is employed to secure the lower end of the plunger rod 30 axially in a collar member 33, said collar member being formed with an axial bore which receives the plunger rod 30 and with a transverse bore 34 through which is inserted the locking pin 31, said locking pin extending through a transverse aperture in the plunger rod 30 to secure said rod to the collar 33. The collar 33 has a reduced lower portion 35 which extends through an annular internal shoulder 36 into the lower portion of the socket 28, as shown in Figure 2. Designated at 37 is a coiled spring surrounding the plunger rod 30 and acting downwardly on the collar member 33, biasing the plunger rod 30 downwardly. When the plunger rod 30 is elevated, as shown in Figure 2, the flexible contact 27 is brought into engagement with the stationary contact 26, allowing the energizing circuit of the power tool to be closed by the main control switch 23.

The bottom wall 38 of the handle is formed with the aperture 39 having the opposed outwardly extending slot portions 40, 40, said aperture 39 being axially aligned with the socket 28. The chuck key 13 is insertable through the aperture 39, the arms 19, 19 being insertable through the opposed slot portions 40, 40. The bottom wall 38 of the handle is formed adjacent the respective slot portions 40, 46 with the apertures 41, 41 adapted to receive the lug elements 20, 20 of the arms 19, 19 when the handle bar 14 is rotated after the chuck key has been inserted into the aperture 39 as above described.

As shown in Figure 2, the chuck key is inserted through the aperture 39 so that the shank thereof extends in axial alignment with the plunger rod 30, the bevel gear portion 16 of the key being received in the socket 23 and engaging the bottom rim of the reduced portion 35 of collar 33. As the key is elevated in the socket, the collar member 33 is raised and the plunger rod 30 is moved upwardly against the flexible contact 27, bringing said contact into engagement with the stationary contact 26. After the arms 19, 19 have been moved upwardly sufiiciently in the handle 21 to allow the key to be rotated, the key is rotated by means of the handle bar 14 to engage the lug elements 20, 20 in the openings 41, 41, whereby the key is locked in stationary position when the handle bar 14 is released, the contact 27 being also locked in engagement with the stationary contact 26 when the chuck key is in this position.

With the chuck key housed in the handle, in the manner above described, the tool may be operated in the usual manner, energization thereof being controlled by the trigger member 24. When it is desired to loosen the chuck 12, the key is removed by following the reverse procedure to that described above, whereupon the plunger rod 30 is lowered by the biasing spring 37, opening the energizing circuit of the tool. Therefore, the tool cannot be operated during the time that the chuck key is out of its housed position in the handle 21. Therefore, the chuck may be loosened or tightened, as desired, without any risk of accidental operation of the power tool during this period. Furthermore, the tool cannot be operated without replacing the chuck key in its housed position shown in Figure 2, whereby loss of the chuck key is effectively prevented, since the operator will realize that the chuck key must be placed back in its housed position in order for the tool to be operated.

While a specific embodiment of an improvement in power tools of the type having a key-operated chuck has been disclosed in the foregoing description, it will be understood that various modifications within the spirit agrsaeoa of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is:

1. In a power tool of the type having. a key-operated chuck, a stationary contact mounted in the tool, a resilient movable contact mounted in said tool and normally engaging said stationary contact, a key socket in said tool and being rigidly secured to said tool, said socket having its inner end located adjacent said movable contact, a key removably positioned in said socket, said key having a stud element projecting axially from its end, slidable plunger means disposed in said. inner end of the socket, said" plunger means being engaged by said axially projecting, stud element and engaging said movable contact to hold said movable contact in engagement with the stationary contact, an abutment element on said plunger means, and a coiled spring surrounding said plunger means and bearing between said abutment element and said inner end of the socket to bias the plunger means away from said movable contact, whereby the switch is opened responsive to the removal or the key.

2'. In a power tool of the type having a key-operated chuck, a stationary contact mounted in the tool, a resilient movable contact mounted in said tool and normally engaging said stationary contact, a key socket in said tool and being rigidly secured to said tool, said socket having its inner end located adjacent said movable contact, said socket extending substantially at right angles to said movable contact, a key removably positioned in said socket, said key having a stud element projecting axially from its end, slidable plunger means disposed axially in said inner end of the socket, said plunger means being engaged by said axially projecting stud element and engaging .said movable contact to hold said movable contact in engagement with the stationary contact, an abutment element On said plunger means, and a coiled spring surrounding said plunger means and bearing between said abutment element and said inner end of the socket to bias the plunger means away from said movable contact, whereby the switch is opened responsive to the removal of the key.

References Cited in the file of this patent UNITED STATES PATENTS 1 ,049,403 Rypinski Jan. 7, 191-3- 2,487,01l Wilhide Nov. 1949' 2,539,123 Dudley Jan. 23, 1951 2,578,317 Pealer Dec. 11, 1951 2,588,565 Pealer Mar. 11, 1952' 2,597,969 Barton May 27, 1952 2,666,104 Griffin Jan. 12, 1954' 

